How to create a class instance without calling initializer?

When feasible, letting __init__ get called (and make the call innocuous by suitable arguments) is preferable. However, should that require too much of a contortion, you do have an alternative, as long as you avoid the disastrous choice of using old-style classes (there is no good reason to use old-style classes in new code, and several good reasons not to)…:

   class String(object):
      ...

   bare_s = String.__new__(String)

This idiom is generally used in classmethods which are meant to work as “alternative constructors”, so you’ll usually see it used in ways such as…:

@classmethod 
def makeit(cls):
    self = cls.__new__(cls)
    # etc etc, then
    return self

(this way the classmethod will properly be inherited and generate subclass instances when called on a subclass rather than on the base class).